We reached out to San Bernardino sheriff's and D.A. officials regarding the hackers' apparent threat but had yet to hear back.

Clifford Neuman, director of USC's Center for Computer Systems Security, explained to us what authorities -- if Anonymous can figure out who it wants to target -- might expect.

Denial of service (DoS): This is perhaps the easiest move for the group to carry out. It simply overwhelms a website with automated requests to view it, taking it down.

Website hacks: This is where members of the group somehow get the keys to a website and change its content and imagery to clown Anonymous' targets.

Document hacks: This is the most serious of the group's alleged actions. In such a case hackers would break into non-public computer systems, obtain sensitive documents (such as someone's personal info or embarrassing memos) and post them online.

Neuman says authorities can defend themselves by ensuring that their websites are hosted off-site, by being extra vigilant about failed password attempts, and by reminding employees to be wary of "fishing," -- official-seeming emails, phone calls and the like seeking reaffirmation of passwords and other sensitive info.

Most of the hacks, Neuman says, are just "an annoyance, an embarrassment," but he says document thefts can be painful to an organization.